1. Field of the Invention
The present invention relates to a flexible circuit board, especially to a flexible circuit board being able to avoid scratching of overlay objects on a flexible substrate.
2. Description of the Related Art
Owing to the coming of digital times, the dependency of people on the electronic products increases. To meet demands of current electronic products such as high speed, high performance and lightweight, flexible circuit boards have gradually been applied in various electronic products, such as notebook computer, mobile phone, digital camera, personal digital assistant, printer and CD-ROM, etc.
The flexible circuit board may be a FPC (Flexible Printed Circuit), a FFC (Flexible Flat Cable) or a thin film switch, which is not only used for electrical connection, but also for carrying chips or other electronic devices. For enabling the cooperation and communication between the chips and other electronic devices, as well as effectively protecting the fragile chips, various package technologies for chips are developed. For example, common wafer bonding technologies include wire bonding, flip-chip and tape automated bonding (TAB), etc. The tape automated bonding is used to bond a chip on a flexible circuit board. Since the flexible circuit board itself is bendable, making the subsequent assembly processes more flexible, and the application becomes more widespread.
FIG. 6 and FIG. 7 schematically illustrate a conventional flexible circuit board being inserted into a connector terminal and a conventional flexible circuit board inserted into a connector terminal. The conventional flexible circuit board comprises a flexible substrate 51 and electrically conductive pads 52 overlaid on an upper surface of the flexible substrate 51. Front ends 54 of the electrically conductive pads 52 are aligned with a front edge 53 of the flexible substrate 51. When an operator pushes the conventional flexible circuit board into a connector terminal 30 for assembly, an upper elastic flat piece 31 and a lower elastic flat piece 32 of the connector terminal 30 will be opened by the conventional flexible circuit board and electrically connect the conventional flexible circuit board. However, during the connecting process of the upper elastic flat piece 31, the lower elastic flat piece 32 and the conventional flexible circuit board, the bent inclined surface of the upper elastic flat piece 31 may scratch (or abrade) the front ends 54 of the electrically conductive pads 52, or even the electrically conductive pads 52 may depart (or be removed) from the conventional flexible circuit board, resulting in that the conventional flexible circuit board cannot electrically connect the connector terminal 30. Thus the conventional flexible circuit board still has disadvantages and need to be improved.